hasToggledState constant Null safety
The semantics node has the quality of either being "on" or "off".
This flag is mutually exclusive with hasCheckedState.
For example, a switch has toggled state.
- SemanticsFlag.isToggled, which controls whether the node is "on" or "off".
static const SemanticsFlag hasToggledState = SemanticsFlag._(_kHasToggledStateIndex);